Polymeric structures comprising a hydrophile

ABSTRACT

Hydroxyl polymer-containing compositions, especially hydroxyl polymer-containing compositions that can be processed into polymeric structures, especially polymeric structures in the form of fibers are provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of prior U.S. application Ser. No.12/731,576 filed Mar. 25, 2010 now U.S. Pat. No. 8,071,203, issued Dec.6, 2011, which is a divisional of prior U.S. application Ser. No.10/988,941 filed Nov. 15, 2004 now U.S. Pat. No. 7,714,065 issued May11, 2010, which is a continuation-in-part of prior U.S. application Ser.No. 10/738,943 filed Dec. 17, 2003, now U.S. Pat. No. 7,426,775 issuedSep. 23, 2008.

FIELD OF THE INVENTION

The present invention relates to hydroxyl polymer-containingcompositions, especially hydroxyl polymer-containing compositions thatcan be processed into polymeric structures, especially polymericstructures in the form of fibers.

BACKGROUND OF THE INVENTION

Polymeric structures and hydroxyl polymer-containing compositions fromwhich the polymeric structures are obtained are generally known in theart. Particularly, hydroxyl polymer-containing polymeric structures suchas starch filaments and/or fibers are generally known in the art.However, starch filaments and/or fibers made by prior art hydroxylpolymer-containing compositions, typically hydroxyl polymer-containingcompositions, and/or polymer processing tend to have a sticky, viscidfeeling and are water swellable and/or soluble. Both of these propertiesof prior art starch filaments and/or fibers negatively impact the use ofsuch filaments and/or fibers in consumer products, especially inproducts such as fibrous structures and/or sanitary tissue products madefrom such fibrous structures.

Accordingly, there exists a need to identify hydroxyl polymer-containingcompositions and/or polymeric structures obtained from such hydroxylpolymer-containing compositions that overcome the disadvantages of theprior art hydroxyl polymer-containing compositions and/or polymericstructures obtained therefrom.

SUMMARY OF THE INVENTION

The present invention fulfills the needs described above by providing ahydroxyl polymer-containing composition and polymeric structuresobtained therefrom that do not suffer from the disadvantages present inthe prior art hydroxyl polymer-containing compositions and polymericstructures obtained therefrom.

In one aspect of the present invention, a hydroxyl polymer-containingcomposition comprising an aqueous mixture comprising a hydroxyl polymer;a hydrophile/lipophile system comprising a hydrophile component and alipophile component; and a crosslinking system comprising a crosslinkingagent; wherein the hydrophile component facilitates dispersibility ofthe lipophile component in the aqueous mixture is provided. In otherwords, the hydrophile component allows the lipophile component to bedistributed uniformly or substantially uniformly throughout the aqueousmixture.

In another aspect of the present invention, a polymeric structurederived from a hydroxyl polymer-containing composition according to thepresent invention is provided.

In yet another aspect of the present invention, a fibrous structurecomprising one or more polymeric structures according to the presentinvention is provided.

In still another aspect of the present invention, a single- or multi-plysanitary tissue product comprising a fibrous structure according to thepresent invention is provided. Preferably, the tissue product exhibits awet yield stress of from about 1000 to about 6000 Pa at a strain of atleast about 1 to about 10 as measured by the Wet Yield Stress TestMethod described herein and/or exhibits a wet bulk of at least about 40%and/or at least about 50% of the dry bulk as measured by the Wet BulkTest Method described herein.

In even another aspect of the present invention, a method for making ahydroxyl polymer-containing composition according to the presentinvention is provided.

In even yet another aspect of the present invention, a method for makinga polymeric structure according to the present invention is provided.

In even still yet another aspect of the present invention, a polymericstructure in fiber form produced according to a method of the presentinvention is provided.

Accordingly, the present invention provides a hydroxylpolymer-containing composition, a polymeric structure derived from thehydroxyl polymer-containing composition, fibrous structures comprisingthe polymeric structures, sanitary tissue products comprising thefibrous structures and methods for making the hydroxylpolymer-containing composition and the polymeric structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic side view of a barrel of a twin screw extrudersuitable for use in the present invention.

FIG. 1B is a schematic side view of a screw and mixing elementconfiguration suitable for use in the barrel of FIG. 1A.

FIG. 2 is a schematic side view of a process for synthesizing apolymeric structure in accordance with the present invention.

FIG. 3 is a schematic partial side view of the process of the presentinvention, showing an attenuation zone.

FIG. 4 is a schematic plan view taken along lines 4-4 of FIG. 3 andshowing one possible arrangement of a plurality of extrusion nozzlesarranged to provide polymeric structures of the present invention.

FIG. 5 is a view similar to that of FIG. 4 and showing one possiblearrangement of orifices for providing a boundary air around theattenuation zone.

DETAILED DESCRIPTION OF THE INVENTION Definitions

“Fiber” or “filament” as used herein means a slender, thin, and highlyflexible object having a major axis which is very long, compared to thefiber's two mutually-orthogonal axes that are perpendicular to the majoraxis. Preferably, an aspect ratio of the major's axis length to anequivalent diameter of the fiber's cross-section perpendicular to themajor axis is greater than 100/1, more specifically greater than 500/1,and still more specifically greater than 1000/1, and even morespecifically, greater than 5000/1. The fibers may be continuous orsubstantially continuous fibers or they may be discontinuous fibers.

The fibers of the present invention may have a fiber diameter of lessthan about 50 microns and/or less than about 20 microns and/or less thanabout 10 microns and/or less than about 8 microns and/or less than about6 microns and/or less than about 4 microns as measured by the FiberDiameter Test Method described herein.

“Spinning process temperature” as used herein means the temperature atwhich the hydroxyl polymer-containing fibers are attenuated at theexternal surface of the rotary spinning die as the hydroxylpolymer-containing fibers are formed.

“Hydroxyl polymer-containing composition” as used herein means acomposition that comprises at least one hydroxyl polymer. In oneexample, the hydroxyl polymer-containing composition comprises at leastone material that doesn't melt before it decomposes. For example, ahydroxyl polymer can dissolve in water, rather than melt, and then canbe dried (removal of water) during a fiber forming process.

A. Hydroxyl Polymer-Containing Composition

The hydroxyl polymer-containing composition of the present inventioncomprises a hydroxyl polymer. “Hydroxyl polymer” as used herein meansany polymer that contains greater than 10% and/or greater than 20%and/or greater than 25% by weight hydroxyl groups.

The hydroxyl polymer-containing composition may be a compositecontaining a blend of polymers, wherein at least one is a hydroxylpolymer, and/or fillers both inorganic and organic, and/or fibers and/orfoaming agents.

The hydroxyl polymer-containing composition may already be foliated. Inone embodiment, the hydroxyl polymer may be solubilized via contact witha liquid, such as water, in order to form the hydroxylpolymer-containing composition. Such a liquid may be considered for thepurposes of the present invention as performing the function of anexternal plasticizer. Alternatively, any other suitable processes knownto those skilled in the art to produce the hydroxyl polymer-containingcomposition such that the hydroxyl polymer-containing compositionexhibits suitable properties for polymer processing the composition intoa polymeric structure in accordance with the present invention may beused.

The hydroxyl polymer-containing composition may have and/or be exposedto a temperature of from about 23° C. to about 100° C. and/or from about65° C. to about 95° C. and/or from about 70° C. to about 90° C. whenmaking polymeric structures from the hydroxyl polymer-containingcomposition. The hydroxyl polymer-containing composition may have and/orbe exposed to a temperature that is generally higher when making filmand/or foam polymeric structures, as described below.

The pH of the hydroxyl polymer-containing composition may be from about2.5 to about 10 and/or from about 3 to about 9.5 and/or from about 3 toabout 8.5 and/or from about 3.2 to about 8 and/or from about 3.2 toabout 7.5.

The hydroxyl polymer-containing composition may have a shear viscosity,as measured according to the Shear Viscosity of a HydroxylPolymer-Containing Composition Test Method described herein, of lessthan about 300 Pa·s and/or from about 0.1 Pa·s to about 300 Pa·s and/orfrom about 1 Pa·s to about 250 Pa·s and/or from about 3 Pa·s to about200 Pa·s as measured at a shear rate of 3,000 sec⁻¹ and at the spinningprocessing temperature.

In one example, the normalized shear viscosity of the hydroxylpolymer-containing composition of the present invention must notincrease more than 1.3 times the initial shear viscosity value after 70minutes and/or 2 times the initial shear viscosity value after 130minutes when measured at a shear rate of 3,000 sec⁻¹ according to theShear Viscosity Change Test Method described herein.

In another example, a hydroxyl polymer-containing composition of thepresent invention may comprise at least about 5% and/or at least about15% and/or from at least about 20% and/or 30% and/or 40% and/or 45%and/or 50% to about 75% and/or 80% and/or 85% and/or 90% and/or 95%and/or 99.5% by weight of the hydroxyl polymer-containing composition ofa hydroxyl polymer. The hydroxyl polymer may have a weight averagemolecular weight greater than about 100,000 g/mol prior to crosslinking.

A crosslinking system may be present in the hydroxyl polymer-containingcomposition and/or may be added to the hydroxyl polymer-containingcomposition before polymer processing of the hydroxyl polymer-containingcomposition.

The hydroxyl polymer-containing composition may comprise a) at leastabout 5% and/or at least about 15% and/or from at least about 20% and/or30% and/or 40% and/or 45% and/or 50% to about 75% and/or 80% and/or 85%by weight of the hydroxyl polymer-containing composition of a hydroxylpolymer; b) a crosslinking system comprising from about 0.1% to about10% by weight of the hydroxyl polymer-containing composition of acrosslinking agent; and c) from about 10% and/or 15% and/or 20% to about50% and/or 55% and/or 60% and/or 70% by weight of the hydroxylpolymer-containing composition of external plasticizer e.g., water.

The crosslinking system of the present invention may further comprise,in addition to the crosslinking agent, a crosslinking facilitator.

“Crosslinking facilitator” as used herein means any material that iscapable of activating a crosslinking agent thereby transforming thecrosslinking agent from its unactivated state to its activated state. Inother words, when a crosslinking agent is in its unactivated state, thehydroxyl polymer present in the hydroxyl polymer-containing compositiondoes not undergo unacceptable crosslinking as determined according tothe Shear Viscosity Change Test Method described herein.

When a crosslinking agent in accordance with the present invention is inits activated state, the hydroxyl polymer present in the polymericstructure may, and preferably does, undergo acceptable crosslinking viathe crosslinking agent as determined according to the Initial Total WetTensile Test Method described herein.

Upon crosslinking the hydroxyl polymer, the crosslinking agent becomesan integral part of the polymeric structure as a result of crosslinkingthe hydroxyl polymer as shown in the following schematic representation:

Hydroxyl Polymer-Crosslinking Agent-Hydroxyl Polymer

The crosslinking facilitator may include derivatives of the materialthat may exist after the transformation/activation of the crosslinkingagent. For example, a crosslinking facilitator salt being chemicallychanged to its acid form and vice versa.

Nonlimiting examples of suitable crosslinking facilitators include acidshaving a pKa of between 2 and 6 or salts thereof. The crosslinkingfacilitators may be Bronsted Acids and/or salts thereof, preferablyammonium salts thereof.

In addition, metal salts, such as magnesium and zinc salts, can be usedalone or in combination with Bronsted Acids and/or salts thereof, ascrosslinking facilitators.

Nonlimiting examples of suitable crosslinking facilitators includeacetic acid, benzoic acid, citric acid, formic acid, glycolic acid,lactic acid, maleic acid, phthalic acid, phosphoric acid, succinic acidand mixtures thereof and/or their salts, preferably their ammoniumsalts, such as ammonium glycolate, ammonium citrate and ammoniumsulfate.

Synthesis of Hydroxyl Polymer-Containing Composition

A hydroxyl polymer-containing composition of the present invention maybe prepared using a screw extruder, such as a vented twin screwextruder.

A barrel 10 of an APV Baker (Peterborough, England) twin screw extruderis schematically illustrated in FIG. 1A. The barrel 10 is separated intoeight zones, identified as zones 1-8. The barrel 10 encloses theextrusion screw and mixing elements, schematically shown in FIG. 1B, andserves as a containment vessel during the extrusion process. A solidfeed port 12 is disposed in zone 1 and a liquid feed port 14 is disposedin zone 1. A vent 16 is included in zone 7 for cooling and decreasingthe liquid, such as water, content of the mixture prior to exiting theextruder. An optional vent stuffer, commercially available from APVBaker, can be employed to prevent the hydroxyl polymer-containingcomposition from exiting through the vent 16. The flow of the hydroxylpolymer-containing composition through the barrel 10 is from zone 1exiting the barrel 10 at zone 8.

A screw and mixing element configuration for the twin screw extruder isschematically illustrated in FIG. 1B. The twin screw extruder comprisesa plurality of twin lead screws (TLS) (designated A and B) and singlelead screws (SLS) (designated C and D) installed in series. Screwelements (A-D) are characterized by the number of continuous leads andthe pitch of these leads.

A lead is a flight (at a given helix angle) that wraps the core of thescrew element. The number of leads indicates the number of flightswrapping the core at any given location along the length of the screw.Increasing the number of leads reduces the volumetric capacity of thescrew and increases the pressure generating capability of the screw.

The pitch of the screw is the distance needed for a flight to completeone revolution of the core. It is expressed as the number of screwelement diameters per one complete revolution of a flight. Decreasingthe pitch of the screw increases the pressure generated by the screw anddecreases the volumetric capacity of the screw.

The length of a screw element is reported as the ratio of length of theelement divided by the diameter of the element.

This example uses TLS and SLS. Screw element A is a TLS with a 1.0 pitchand a 1.5 length ratio. Screw element B is a TLS with a 1.0 pitch and a1.0 L/D ratio. Screw element C is a SLS with a ¼ pitch and a 1.0 lengthratio. Screw element D is a SLS and a ¼ pitch and a ½ length ratio.

Bilobal paddles, E, serving as mixing elements, are also included inseries with the SLS and TLS screw elements in order to enhance mixing.Various configurations of bilobal paddles and reversing elements F,single and twin lead screws threaded in the opposite direction, are usedin order to control flow and corresponding mixing time.

In zone 1, the hydroxyl polymer is fed into the solid feed port at arate of 230 grams/minute using a K-Tron (Pitman, N.J.) loss-in-weightfeeder. This hydroxyl polymer is combined inside the extruder (zone 1)with water, an external plasticizer, added at the liquid feed at a rateof 146 grams/minute using a Milton Roy (Ivyland, Pa.) diaphragm pump(1.9 gallon per hour pump head) to form a hydroxyl polymer/water slurry.This slurry is then conveyed down the barrel of the extruder and cooked.Table 1 describes the temperature, pressure, and corresponding functionof each zone of the extruder.

TABLE I Temp. Description Zone (° F.) Pressure of Screw Purpose 1 70 LowFeeding/Conveying Feeding and Mixing 2 70 Low Conveying Mixing andConveying 3 70 Low Conveying Mixing and Conveying 4 130 LowPressure/Decreased Conveying and Heating Conveying 5 300 Medium PressureGenerating Cooking at Pressure and Temperature 6 250 High ReversingCooking at Pressure and Temperature 7 210 Low Conveying Cooling andConveying (with venting) 8 210 Low Pressure Generating Conveying

After the slurry exits the extruder, part of the hydroxyl polymer/waterslurry is dumped and another part (100 g) is fed into a Zenith®, typePEP II (Sanford N.C.) and pumped into a SMX style static mixer(Koch-Glitsch, Woodridge, Ill.). The static mixer is used to combineadditional additives such as crosslinking agents, crosslinkingfacilitators, external plasticizers, such as water, with the hydroxylpolymer/water slurry to form a hydroxyl polymer-containing composition.The additives are pumped into the static mixer via PREP 100 HPLC pumps(Chrom Tech, Apple Valley Minn.). These pumps provide high pressure, lowvolume addition capability. The hydroxyl polymer-containing compositionof the present invention is ready to be polymer processed into ahydroxyl polymer-containing polymeric structure.

B. Polymer Processing

“Polymer processing” as used herein means any operation and/or processby which a polymeric structure comprising a hydroxyl polymer is formedfrom a hydroxyl polymer-containing composition.

Nonlimiting examples of polymer processing operations include extrusion,molding and/or fiber spinning. Extrusion and molding (either casting orblown), typically produce films, sheets and various profile extrusions.Molding may include injection molding, blown molding and/or compressionmolding. Fiber spinning may include spun bonding, melt blowing,continuous filament producing and/or tow fiber producing.

C. Polymeric Structure

The hydroxyl polymer-containing composition can be subjected to one ormore polymer processing operations such that the hydroxylpolymer-containing composition is processed into a polymeric structurecomprising the hydroxyl polymer and optionally, a crosslinking system,according to the present invention.

“Polymeric structure” as used herein means any physical structure formedas a result of processing a hydroxyl polymer-containing composition inaccordance with the present invention. Nonlimiting examples of polymericstructures in accordance with the present invention include fibers,films and/or foams.

The crosslinking system via the crosslinking agent crosslinks hydroxylpolymers together to produce the polymeric structure of the presentinvention, with or without being subjected to a curing step. In otherwords, the crosslinking system in accordance with the present inventionacceptably crosslinks, as determined by the Initial Total Wet TensileTest Method described herein, the hydroxyl polymers of a processedhydroxyl polymer-containing composition together via the crosslinkingagent to form an integral polymeric structure. The crosslinking agent isa “building block” for the polymeric structure. Without the crosslinkingagent, no polymeric structure in accordance with the present inventioncould be formed.

Polymeric structures of the present invention do not include coatingsand/or other surface treatments that are applied to a pre-existing form,such as a coating on a fiber, film or foam.

In one embodiment, the polymeric structure produced via a polymerprocessing operation may be cured at a curing temperature of from about110° C. to about 200° C. and/or from about 120° C. to about 195° C.and/or from about 130° C. to about 185° C. for a time period of fromabout 0.01 and/or 1 and/or 5 and/or 15 seconds to about 60 minutesand/or from about 20 seconds to about 45 minutes and/or from about 30seconds to about 30 minutes. Alternative curing methods may includeradiation methods such as UV, e-beam, IR and other temperature-raisingmethods.

Further, the polymeric structure may also be cured at room temperaturefor days, either after curing at above room temperature or instead ofcuring at above room temperature.

The polymeric structure may exhibit an initial total wet tensile, asmeasured by the Initial Total Wet Tensile Test Method described herein,of at least about 1.18 g/cm (3 g/in) and/or at least about 1.57 g/cm (4g/in) and/or at least about 1.97 g/cm (5 g/in) to about 23.62 g/cm (60g/in) and/or to about 21.65 g/cm (55 g/in) and/or to about 19.69 g/cm(50 g/in).

In one embodiment, a polymeric structure of the present invention maycomprise from at least about 20% and/or 30% and/or 40% and/or 45% and/or50% to about 75% and/or 80% and/or 85% and/or 90% and/or 95% and/or99.5% by weight of the polymeric structure of a hydroxyl polymer.

In one embodiment, the polymeric structure exhibits a contact angle ofless than 40° after 1 second as measured by the Contact Angle TestMethod described herein.

The polymeric structures of the present invention may include melt spunfibers and/or spunbond fibers, staple fibers, hollow fibers, shapedfibers, such as multi-lobal fibers and multicomponent fibers, especiallybicomponent fibers. The multicomponent fibers, especially bicomponentfibers, may be in a side-by-side, sheath-core, segmented pie, ribbon,islands-in-the-sea configuration, or any combination thereof. The sheathmay be continuous or non-continuous around the core. The ratio of theweight of the sheath to the core can be from about 5:95 to about 95:5.The fibers of the present invention may have different geometries thatinclude round, elliptical, star shaped, rectangular, and other variouseccentricities.

The fibers of the present invention may have a fiber diameter of lessthan about 50 microns and/or less than about 20 microns and/or less thanabout 10 microns and/or less than about 8 microns and/or less than about6 microns and/or less than about 4 microns as measured by the FiberDiameter Test Method described herein.

In another embodiment, the polymeric structures of the present inventionmay include a multiconstituent polymeric structure, such as amulticomponent fiber, comprising a hydroxyl polymer of the presentinvention along with another polymer. A multicomponent fiber, as usedherein, means a fiber having more than one separate part in spatialrelationship to one another. Multicomponent fibers include bicomponentfibers, which is defined as a fiber having two separate parts in aspatial relationship to one another. The different components ofmulticomponent fibers can be arranged in substantially distinct regionsacross the cross-section of the fiber and extend continuously along thelength of the fiber.

A nonlimiting example of such a multicomponent fiber, specifically abicomponent fiber, is a bicomponent fiber in which the hydroxyl polymerof the present invention represents the core of the fiber and anotherpolymer represents the sheath, which surrounds or substantiallysurrounds the core of the fiber. The hydroxyl polymer-containingcomposition from which such a polymeric structure is derived may includeboth the hydroxyl polymer and the other polymer.

In another multicomponent, especially bicomponent fiber embodiment, thesheath may comprise a hydroxyl polymer and a crosslinking system havinga crosslinking agent, and the core may comprise a hydroxyl polymer and acrosslinking system having a crosslinking agent. With respect to thesheath and core, the hydroxyl polymer may be the same or different andthe crosslinking agent may be the same or different. Further, the levelof hydroxyl polymer may be the same or different and the level ofcrosslinking agent may be the same or different.

One or more polymeric structures of the present invention may beincorporated into a multi-polymeric structure product, such as a fibrousstructure and/or web, if the polymeric structures are in the form offibers. Such a multi-polymeric structure product may ultimately beincorporated into a commercial product, such as a single- or multi-plysanitary tissue product, such as facial tissue, bath tissue, papertowels and/or wipes, feminine care products, diapers, writing papers,cores, such as tissue cores, and other types of paper products.

Synthesis of Polymeric Structure

Nonlimiting examples of processes for preparing polymeric structures inaccordance with the present invention follow.

i) Fiber Formation

A hydroxyl polymer-containing composition is prepared according to theSynthesis of a Hydroxyl Polymer-Containing Composition described above.As shown in FIG. 2, the hydroxyl polymer-containing composition may beprocessed into a polymeric structure. The hydroxyl polymer-containingcomposition present in an extruder 102 is pumped to a die 104 using pump103, such as a Zenith®, type PEP II, having a capacity of 0.6 cubiccentimeters per revolution (cc/rev), manufactured by Parker HannifinCorporation, Zenith Pumps division, of Sanford, N.C., USA. The hydroxylpolymer's, such as starch, flow to die 104 is controlled by adjustingthe number of revolutions per minute (rpm) of the pump 103. Pipesconnecting the extruder 102, the pump 103, the die 104, and optionally amixer 116 are electrically heated and thermostatically controlled to 65°C.

The die 104 has several rows of circular extrusion nozzles 200 spacedfrom one another at a pitch P (FIG. 3) of about 1.524 millimeters (about0.060 inches). The nozzles 200 have individual inner diameters D2 ofabout 0.305 millimeters (about 0.012 inches) and individual outsidediameters (D1) of about 0.813 millimeters (about 0.032 inches). Eachindividual nozzle 200 is encircled by an annular and divergently flaredorifice 250 formed in a plate 260 (FIGS. 3 and 4) having a thickness ofabout 1.9 millimeters (about 0.075 inches). A pattern of a plurality ofthe divergently flared orifices 250 in the plate 260 correspond to apattern of extrusion nozzles 200. The orifices 250 have a largerdiameter D4 (FIGS. 3 and 4) of about 1.372 millimeters (about 0.054inches) and a smaller diameter D3 of 1.17 millimeters (about 0.046inches) for attenuation air. The plate 260 was fixed so that theembryonic fibers 110 being extruded through the nozzles 200 aresurrounded and attenuated by generally cylindrical, humidified airstreams supplied through the orifices 250. The nozzles can extend to adistance from about 1.5 mm to about 4 mm, and more specifically fromabout 2 mm to about 3 mm, beyond a surface 261 of the plate 260 (FIG.3). As shown in FIG. 5, a plurality of boundary-air orifices 300, isformed by plugging nozzles of two outside rows on each side of theplurality of nozzles, as viewed in plane, so that each of theboundary-layer orifice comprised a annular aperture 250 described hereinabove. Additionally, every other row and every other column of theremaining capillary nozzles are blocked, increasing the spacing betweenactive capillary nozzles

As shown in FIG. 2, attenuation air can be provided by heatingcompressed air from a source 106 by an electrical-resistance heater 108,for example, a heater manufactured by Chromalox, Division of EmersonElectric, of Pittsburgh, Pa., USA. An appropriate quantity of steam 105at an absolute pressure of from about 240 to about 420 kiloPascals(kPa), controlled by a globe valve (not shown), is added to saturate ornearly saturate the heated air at the conditions in the electricallyheated, thermostatically controlled delivery pipe 115. Condensate isremoved in an electrically heated, thermostatically controlled,separator 107. The attenuating air has an absolute pressure from about130 kPa to about 310 kPa, measured in the pipe 115. The polymericstructure fibers 110 being extruded have a moisture content of fromabout 20% and/or 25% to about 50% and/or 55% by weight. The polymerstructure fibers 110 are dried by a drying air stream 109 having atemperature from about 149° C. (about 300° F.) to about 315° C. (about600° F.) by an electrical resistance heater (not shown) supplied throughdrying nozzles 112 and discharged at an angle generally perpendicularrelative to the general orientation of the embryonic fibers beingextruded. The polymeric structure fibers are dried from about 45%moisture content to about 15% moisture content (i.e., from a consistencyof about 55% to a consistency of about 85%) and are collected on acollection device 111, such as, for example, a movable foraminous belt.

The process parameters are as follows.

Sample Units Attenuation Air Flow Rate G/min 2500 Attenuation AirTemperature ° C. 93 Attenuation Steam Flow Rate G/min 500 AttenuationSteam Gage Pressure kPa 213 Attenuation Gage Pressure in kPa 26 DeliveryPipe Attenuation Exit Temperature ° C. 71 Solution Pump Speed Revs/min35 Solution Flow G/min/hole 0.18 Drying Air Flow Rate g/min 10200 AirDuct Type Slots Air Duct Dimensions Mm 356 × 127 Velocity viaPitot-Static Tube M/s 34 Drying Air Temperature at Heater ° C. 260 DryDuct Position from Die Mm 80 Drying Duct Angle Relative to degrees 0Fibersii) Foam Formation

The hydroxyl polymer-containing composition for foam formation isprepared similarly as for fiber formation except that the water contentwill be less, typically from about 10-21% of the hydroxyl polymerweight. With less water to plasticize the hydroxyl polymer, highertemperatures may be needed in extruder zones 5-8 (FIG. 1A), typicallyfrom 150-250° C. Also with less water available, it may be necessary toadd the crosslinking system, especially the crosslinking agent, with thewater in zone 1. In order to avoid premature crosslinking in theextruder, the hydroxyl polymer-containing composition pH should bebetween 7 and 8, achievable by using a crosslinking facilitator e.g.,ammonium salt. A die is placed at the location where the extrudedmaterial emerges and is typically held at 160-210° C. Modified highamylose starches (for example greater than 50% and/or greater than 75%and/or greater than 90% by weight of the starch of amylose) granulatedto particle sizes ranging from 400-1500 microns are preferred for thisapplication. It may also be advantageous to add a nucleating agent suchas microtalc or alkali metal or alkaline earth metal salt such as sodiumsulfate or sodium chloride in an amount of about 1-8% of the starchweight. The foam may be shaped into various forms.

iii) Film Formation

The hydroxyl polymer-containing composition for film formation isprepared similarly as for foam formation except that the added watercontent is less, typically 3-15% of the hydroxyl polymer weight and apolyol external plasticizer such as glycerol is included at 10-30% ofthe hydroxyl polymer weight. As with foam formation, zones 5-7 (FIG. 1A)are held at 160-210° C., however, the slit die temperature is lowerbetween 60-120° C. As with foam formation, the crosslinking system,especially the crosslinking agent, may be added along with the water inzone 1 and the hydroxyl polymer-containing composition pH should bebetween 7-8 achievable by using a crosslinking facilitator e.g.,ammonium salt.

Films of the present invention may be utilized for any suitable productsknown in the art. For example, the films may be used in packagingmaterials.

Hydroxyl Polymers

Hydroxyl polymers in accordance with the present invention include anyhydroxyl-containing polymer that can be incorporated into a polymericstructure of the present invention, preferably in the form of a fiber orfilament.

In one embodiment, the hydroxyl polymer of the present inventionincludes greater than 10% and/or greater than 20% and/or greater than25% by weight hydroxyl moieties.

Nonlimiting examples of hydroxyl polymers in accordance with the presentinvention include polyols, such as starch and starch derivatives,cellulose derivatives such as cellulose ether and ester derivatives,chitosan and chitosan derivatives, polyvinylalcohols and various otherpolysaccharides such as gums, arabinans and galactans, and proteins.

The hydroxyl polymer preferably has a weight average molecular weight ofgreater than about 10,000 g/mol and/or greater than about 40,000 g/moland/or from about 10,000 to about 80,000,000 g/mol and/or from about10,000 to about 40,000,000 g/mol and/or from about 10,000 to about10,000,000 g/mol. Higher and lower molecular weight hydroxyl polymersmay be used in combination with hydroxyl polymers having the preferredweight average molecular weight. “Weight average molecular weight” asused herein means the weight average molecular weight as determinedusing gel permeation chromatography according to the protocol found inColloids and Surfaces A. Physico Chemical & Engineering Aspects, Vol.162, 2000, pg. 107-121.

A natural starch can be modified chemically or enzymatically, as wellknown in the art. For example, the natural starch can be acid-thinned,hydroxy-ethylated or hydroxy-propylated or oxidized.

“Polysaccharides” herein means natural polysaccharides andpolysaccharide derivatives or modified polysaccharides. Suitablepolysaccharides include, but are not limited to, gums, arabinans,galactans and mixtures thereof.

Polyvinylalcohols which are suitable for use as the hydroxyl polymers(alone or in combination) of the present invention can be characterizedby the following general formula:

each R is selected from the group consisting of C₁-C₄ alkyl; C₁-C₄ acyl;and x/x+y+z=0.5-1.0.Hydrophile/Lipophile System

The hydrophile/lipophile system of the present invention comprises ahydrophile component and a lipophile component. The hydrophile/lipophilesystem exhibits a Tg of less than about 40° and/or less than about 25°to about −30° C. and/or to about −15° C.

Nonlimiting examples of hydrophile/lipophile systems comprise aningredient selected from the group consisting of: latex graftedstarches, styrene/butadiene latexes, vinyl/acrylic latexes, acryliclatexes, acrylate modified latexes, water dispersible fluoropolymers,water dispersible silicones and mixtures thereof.

In one embodiment, the hydrophile/lipophile system exhibits an averageparticle size (as measured by LB 500, commercially available from HoribaInternational, Irving, Calif.) of from about 10 nm and/or from about 75nm and/or from about 100 nm to about 6 μm and/or to about 3 μm and/or toabout 1.5 μm. In one embodiment, the hydrophile/lipophile systemexhibits an average particle size of from about 10 nm to about 6 μm.

In one embodiment, the hydrophile component and the lipophile componentare covalently bonded together.

In another embodiment, the hydrophile component and the lipophilecomponent are not covalently bonded together.

In one embodiment, the hydrophile component and the lipophile componentare present in the hydrophile/lipophile system at a weight percenthydrophile component to weight percent lipophile component of from about30:70 to about 1:99 and/or from about 20:80 to about 5:95.

In still another embodiment, the hydrophile/lipophile system is presentin the hydroxyl polymer-containing composition of the present inventionat a level of from about 0.5% and/or from about 1% to about 3% and/or toabout 10% by weight of the starch.

In one embodiment, the hydrophile/lipophile system comprises adiscontinuous phase within the hydroxyl polymer. In other words, thehydroxyl polymer may be present in a continuous phase and thehydrophile/lipophile system may be present in a discontinuous phasewithin the continuous phase of the hydroxyl polymer.

a. Hydrophile Component

Nonlimiting examples of suitable hydrophile components are selected fromthe group consisting of: alkylaryl sulfonates, ethoxylated alcohols,ethoxylated alkylphenols, ethoxylated amines, ethoxylated fatty acids,ethoxylated fatty esters and oils, glycerol esters, propoxylated &ethoxylated fatty acids, propoxylated & ethoxylated fatty alcohols,propoxylated & ethoxylated alkyl phenols, quaternary surfactants,sorbitan derivitaives, alcohol sulfates, ethoxylated alcohol sulfates,sulfosuccinates and mixtures thereof.

b. Lipophile Component

Nonlimiting examples of suitable lipophile components are selected fromthe group consisting of: saturated and unsaturated animal and vegetableoils, mineral oil, petrolatum, natural and synthetic waxes and mixturesthereof.

c. Surfactant Component

The hydrophile/lipophile system of the present invention may comprise asurfactant component that may or may not also function as a hydrophilecomponent. A nonlimiting example of a suitable surfactant componentincludes siloxane-based surfactants and organosulfosuccinatesurfactants.

One class of suitable surfactant component materials can includesiloxane-based surfactants (siloxane-based materials). Thesiloxane-based surfactants in this application may be siloxane polymersfor other applications. The siloxane-based surfactants typically have aweight average molecular weight from 500 to 20,000 g/mol. Suchmaterials, derived from poly(dimethylsiloxane), are well known in theart.

Nonlimiting commercially available examples of suitable siloxane-basedsurfactants are TSF 4446 and Nu Wet 550 and 625, and XS69-B5476(commercially available from General Electric Silicones); Jenamine HSX(commercially available from DelCon), Silwet L7087, L7200, L8620, L77and Y12147 (commercially available from OSi Specialties).

A second preferred class of suitable surfactant component materials isorganic in nature. Preferred materials are organosulfosuccinatesurfactants, with carbon chains of from about 6 to about 20 carbonatoms. Most preferred are organosulfosuccinates containing dialklychains, each with carbon chains of from about 6 to about 20 carbonatoms. Also preferred are chains containing aryl or alkyl aryl,substituted or unsubstituted, branched or linear, saturated orunsaturated groups.

Nonlimiting commercially available examples of suitableorganosulfosuccinate surfactants are available under the trade names ofAerosol OT and Aerosol TR-70 (ex. Cytec).

In one embodiment, the surfactant, when present, may be present in thehydroxyl polymer-containing composition of the present invention at alevel of from about 0.01% to about 0.5% and/or from about 0.025% toabout 0.4% and/or from about 0.05% to about 0.30% by weight of thestarch(hydroxyl polymer?).

Crosslinking System

“Crosslinking system” as used herein means a crosslinking system thatcomprises a crosslinking agent and optionally a crosslinking facilitatorwherein a hydroxyl polymer-containing composition within which thecrosslinking system is present exhibits less than a 1.3 times normalizedshear viscosity change after 70 minutes and/or less than a 2 timesnormalized shear viscosity change after 130 minutes according to theShear Viscosity Change Test Method described herein. Crosslinking agentsand/or crosslinking systems that do not satisfy this test method do notfall within the scope of the present invention.

Preferably, a polymeric structure produced from the hydroxylpolymer-containing composition comprising the crosslinking system of thepresent invention exhibits an initial total wet tensile, as measured bythe Initial Total Wet Tensile Test Method described herein, of at leastabout 1.18 g/cm (3 g/in) and/or at least about 1.57 g/cm (4 g/in) and/orat least about 1.97 g/cm (5 g/in) to about 23.62 g/cm (60 g/in) and/orto about 21.65 g/cm (55 g/in) and/or to about 19.69 g/cm (50 g/in).

The level of crosslinking agent, type of crosslinking agent, level ofcrosslinking facilitator, if any, and type of crosslinking facilitator,if any, within the crosslinking system of the present invention arefactors that may impact whether the crosslinking system is unacceptableunder the Shear Viscosity Change Test Method and/or provides acceptablecrosslinking of a hydroxyl polymer under the Initial Total Wet TensileTest Method.

“Crosslinking agent” as used herein means any material that is capableof crosslinking a hydroxyl polymer within a hydroxyl polymer-containingcomposition according to the present.

Nonlimiting examples of suitable crosslinking agents include compoundsresulting from alkyl substituted or unsubstituted cyclic adducts ofglyoxal with ureas (Structure V, X═O), thioureas (Structure V, X═S),guanidines (Structure V, X═NH, N-alkyl), methylene diamides (StructureVI), and methylene dicarbamates (Structure VII) and derivatives thereof;and mixtures thereof.

In one embodiment, the crosslinking agent has the following structure:

wherein X is O or S or NH or N-alkyl, and R₁ and R₂ are independently

wherein R₃ and R₈ are independently selected from the group consistingof: H, linear or branched C₁-C₄ alkyl, CH₂OH and mixtures thereof, R₄ isindependently selected from the group consisting of: H, linear orbranched C₁-C₄ alkyl, and mixtures thereof; x is 0-100; and q is 0-10,R_(H) is independently selected from the group consisting of: H, linearor branched C₁-C₄ alkyl, and mixtures thereof.

In one embodiment, R₃, R₈ and R₄ are not all C₁-C₄ alkyl in a singleunit.

In yet another embodiment, only one of R₃, R₈ and R₄ is C₁-C₄ alkyl in asingle unit.

In another embodiment, the crosslinking agent has the followingstructure:

wherein R₂ is independently

wherein R₃ and R₈ are independently selected from the group consistingof: H, linear or branched C₁-C₄ alkyl, CH₂OH and mixtures thereof, R₄ isindependently selected from the group consisting of: H, linear orbranched C₁-C₄ alkyl, and mixtures thereof; x is 0-100; and q is 0-10,R_(H) are independently selected from the group consisting of: H, linearor branched C₁-C₄ alkyl, and mixtures thereof.

In one embodiment, R₃, R₈ and R₄ are not all C₁-C₄ alkyl in a singleunit.

In yet another embodiment, only one of R₃, R₈ and R₄ is C₁-C₄ alkyl in asingle unit.

In still another embodiment, the crosslinking agent has the followingstructure:

wherein R₂ is independently

wherein R₃ and R₈ are independently selected from the group consistingof: H, linear or branched C₁-C₄ alkyl, CH₂OH and mixtures thereof, R₄ isindependently selected from the group consisting of: H, linear orbranched C₁-C₄ alkyl, and mixtures thereof; x is 0-100; and q is 0-10,R_(H) are independently selected from the group consisting of: H, linearor branched C₁-C₄ alkyl, and mixtures thereof.

In one embodiment, R₃, R₈ and R₄ are not all C₁-C₄ alkyl in a singleunit.

In yet another embodiment, only one of R₃, R₈ and R₄ is C₁-C₄ alkyl in asingle unit.

In yet other embodiments, the crosslinking agent has one of thefollowing structures (Structure VIII, IX and X):

wherein X is O or S or NH or N-alkyl, and R₁ and R₂ are independently

wherein R₃ and R₈ are independently selected from the group consistingof: H, linear or branched C₁-C₄ alkyl, CH₂OH and mixtures thereof, R₄ isindependently selected from the group consisting of: H, linear orbranched C₁-C₄ alkyl, and mixtures thereof; x is 0-100; and q is 0-10,R_(H) is independently selected from the group consisting of: H, linearor branched C₁-C₄ alkyl, and mixtures thereof; x is 0-100; y is 1-50; R₅is independently selected from the group consisting of: —(CH₂)_(n)—wherein n is 1-12, —(CH₂CH(OH)CH₂)—,

wherein R₆ and R₇ are independently selected from the group consistingof: H, linear or branched C₁-C₄ alkyl and mixtures thereof, wherein R₆and R₇ cannot both be C₁-C₄ alkyl within a single unit; and z is 1-100.

In one embodiment, R₃, R₈ and R₄ are not all C₁-C₄ alkyl in a singleunit.

In yet another embodiment, only one of R₃, R₈ and R₄ is C₁-C₄ alkyl in asingle unit.

The crosslinking agent may have the following structure:

wherein R₁ and R₂ are independently

wherein R₃ and R₈ are independently selected from the group consistingof: H, linear or branched C₁-C₄ alkyl, CH₂OH and mixtures thereof, R₄ isindependently selected from the group consisting of: H, linear orbranched C₁-C₄ alkyl, and mixtures thereof; x is 0-100; and q is 0-10,R_(H) is independently selected from the group consisting of: H, linearor branched C₁-C₄ alkyl, and mixtures thereof; x is 1-100; y is 1-50; R₅is independently —(CH₂)_(n)— wherein n is 1-12.

In one embodiment, R₃, R₈ and R₄ are not all C₁-C₄ alkyl in a singleunit.

In yet another embodiment, only one of R₃, R₈ and R₄ is C₁-C₄ alkyl in asingle unit.

In even another embodiment, the crosslinking agent has the followingstructure:

wherein R₁ and R₂ are independently

wherein R₃ and R₈ are independently selected from the group consistingof: H, linear or branched C₁-C₄ alkyl, CH₂OH and mixtures thereof, R₄ isindependently selected from the group consisting of: H, linear orbranched C₁-C₄ alkyl, and mixtures thereof; x is 0-100; and q is 0-10,R_(H) is independently selected from the group consisting of: H, linearor branched C₁-C₄ alkyl, and mixtures thereof; x is 1-100; y is 1-50; R₅is independently selected from the group consisting of: —(CH₂)_(n)—wherein n is 1-12, —(CH₂CH(OH)CH₂)—,

wherein R₆ and R₇ are independently selected from the group consistingof: H, linear or branched C₁-C₄ alkyl and mixtures thereof, wherein R₆and R₇ cannot both be C₁-C₄ alkyl within a single unit; and z is 1-100.

In one embodiment, R₃, R₈ and R₄ are not all C₁-C₄ alkyl in a singleunit.

In yet another embodiment, only one of R₃, R₈ and R₄ is C₁-C₄ alkyl in asingle unit.

In one embodiment, the crosslinking agent comprises an imidazolidinone(Structure V, X═O) where R₂═H, Me, Et, Pr, Bu, (CH₂CH₂O)_(p)H,(CH₂CH(CH₃)O)_(p)H, (CH(CH₃)CH₂O)_(p)H where p is 0-100 and R₁=methyl. Acommercially available crosslinking agent discussed above; namely,Fixapret NF from BASF, has R₁=methyl, R₂═H.

In another embodiment, the crosslinking agent comprises animidazolidinone (Structure V, X═O) where R₂═H, Me, Et, Pr, Bu and R₁═H.Dihydroxyethyleneurea (DHEU) comprises an imidazolidinone (Structure V,X═O) where both R₁ and R₂ are H. DHEU can be synthesized according tothe procedure in EP Patent 0 294 007 A1.

Not being bound by theory, the crosslinking system functions by linkinghydroxyl polymer chains together via amidal linkages as depicted in thefollowing structure. After crosslinking the crosslinker is part of thepolymeric structure.

One of ordinary skill in the art understands that in all the formulasabove, the carbons to which the OR₂ moiety is bonded, also are bonded toa H, which is not shown in the structures for simplicity reasons.

Nonlimiting examples of commercially available crosslinking agents whichare not part of the invention because they are unacceptable asdetermined by the Shear Viscosity Change Test Method and/or the InitialTotal Wet Tensile Test Method described herein include Permafresh EFC(available from OMNOVA Solutions, Inc), Fixapret ECO (available fromBASF) and Parez 490 (available from Bayer Corporation).

Other Ingredients

The hydroxyl polymer-containing composition of the present invention mayfurther comprise an additive selected from the group consisting of:plasticizers, diluents, oxidizing agents, emulsifiers, debonding agents,lubricants, processing aids, optical brighteners, antioxidants, flameretardants, dyes, pigments, fillers, other proteins and salts thereof,other polymers, such as thermoplastic polymers, tackifying resins,extenders, wet strength resins and mixtures thereof.

Methods for Making a Hydroxyl Polymer-Containing Composition

In one embodiment, a method for making a hydroxyl polymer-containingcomposition comprising the steps of:

-   -   a. providing an aqueous mixture comprising a hydroxyl polymer;    -   b. adding a hydrophile/lipophile system to the aqueous mixture,        wherein the hydrophile/lipophile system comprises a hydrophile        component and a lipophile component wherein the hydrophile        component facilitates dispersibility of the lipophile component        into the aqueous mixture; and    -   c. adding a crosslinking system comprising a crosslinking agent        to the aqueous mixture, is provided.

In another embodiment, a method for making a polymeric structurecomprising the steps of:

-   -   a. providing a hydroxyl polymer-containing composition        comprising an aqueous mixture comprising a hydroxyl polymer, a        hydrophile/lipophile system comprising a hydrophile component        and a lipophile component wherein the hydrophile component        facilitates the dispersibility of the lipophile component into        the aqueous mixture and a crosslinking system comprising a        crosslinking agent; and    -   b. polymer processing the hydroxyl polymer-containing        composition to form the polymeric structure, is provided.        Test Methods        A. Shear Viscosity of a Hydroxyl Polymer-Containing Composition        Test Method

The shear viscosity of a hydroxyl polymer-containing composition of thepresent invention is measured using a capillary rheometer, GoettfertRheograph 6000, manufactured by Goettfert USA of Rock Hill S.C., USA.The measurements are conducted using a capillary die having a diameter Dof 1.0 mm and a length L of 30 mm (i.e., L/D=30). The die is attached tothe lower end of the rheometer's 20 mm barrel, which is held at a dietest temperature of 75° C. A preheated to die test temperature, 60 gsample of the hydroxyl polymer-containing composition is loaded into thebarrel section of the rheometer. Rid the sample of any entrapped air.Push the sample from the barrel through the capillary die at a set ofchosen rates 1,000-10,000 seconds⁻¹. An apparent shear viscosity can becalculated with the rheometer's software from the pressure drop thesample experiences as it goes from the barrel through the capillary dieand the flow rate of the sample through the capillary die. The log(apparent shear viscosity) can be plotted against log (shear rate) andthe plot can be fitted by the power law, according to the formula

η=Kγ^(n-1), wherein K is the material's viscosity constant, n is thematerial's thinning index and γ is the shear rate. The reported apparentshear viscosity of the composition herein is calculated from aninterpolation to a shear rate of 3,000 sec⁻¹ using the power lawrelation.B. Shear Viscosity Change Test Method

Viscosities of three samples of a single hydroxyl polymer-containingcomposition of the present invention comprising a crosslinking system tobe tested are measured by filling three separate 60 cc syringes; theshear viscosity of one sample is measured immediately (initial shearviscosity) (it takes about 10 minutes from the time the sample is placedin the rheometer to get the first reading) according to the ShearViscosity of a Hydroxyl Polymer-Containing Composition Test Method. Ifthe initial shear viscosity of the first sample is not within the rangeof 5-8 Pa·s as measured at a shear rate of 3,000 sec⁻¹, then the singlehydroxyl polymer-containing composition has to be adjusted such that thesingle hydroxyl polymer-containing composition's initial shear viscosityis within the range of 5-8 Pa·s as measured at a shear rate of 3,000sec⁻¹ and this Shear Viscosity Change Test Method is then repeated. Oncethe initial shear viscosity of the hydroxyl polymer-containingcomposition is within the range of 5-8 Pa·s as measured at a shear rateof 3,000 sec-1, then the other two samples are measured by the same testmethod after being stored in a convection oven at 80° C. for 70 and 130minutes, respectively. The shear viscosity at 3000 sec⁻¹ for the 70 and130 minute samples is divided by the initial shear viscosity to obtain anormalized shear viscosity change for the 70 and 130 minute samples. Ifthe normalized shear viscosity change is 1.3 times or greater after 70minutes and/or is 2 times or greater after 130 minutes, then thecrosslinking system within the hydroxyl polymer-containing compositionis unacceptable, and thus is not within the scope of the presentinvention. However, if the normalized shear viscosity change is lessthan 1.3 times after 70 minutes and/or (preferably and) is less than 2times after 130 minutes, then the crosslinking system is notunacceptable, and thus it is within the scope of the present inventionwith respect to hydroxyl polymer-containing compositions comprising thecrosslinking system. Preferably, the crosslinking system is acceptablewith respect to polymeric structures derived from hydroxylpolymer-containing compositions comprising the crosslinking system asdetermined by the Initial Total Wet Tensile Test Method.

Preferably, the normalized shear viscosity changes will be less than 1.2times after 70 minutes and/or less than 1.7 times after 130 minutes;more preferably less than 1.1 times after 70 minutes and/or less than1.4 times after 130 minutes.

C. Initial Total Wet Tensile Test Method

An electronic tensile tester (Thwing-Albert EJA Materials Tester,Thwing-Albert Instrument Co., 10960 Dutton Rd., Philadelphia, Pa.,19154) is used and operated at a crosshead speed of 4.0 inch (about10.16 cm) per minute and a gauge length of 1.0 inch (about 2.54 cm),using a strip of a polymeric structure of 1 inch wide and a lengthgreater than 3 inches long. The two ends of the strip are placed in theupper jaws of the machine, and the center of the strip is placed arounda stainless steel peg (0.5 cm in diameter). After verifying that thestrip is bent evenly around the steel peg, the strip is soaked indistilled water at about 20° C. for a soak time of 5 seconds beforeinitiating cross-head movement. The initial result of the test is anarray of data in the form load (grams force) versus crossheaddisplacement (centimeters from starting point).

The sample is tested in two orientations, referred to here as MD(machine direction, i.e., in the same direction as the continuouslywound reel and forming fabric) and CD (cross-machine direction, i.e.,90° from MD). The MD and CD wet tensile strengths are determined usingthe above equipment and calculations in the following manner:Initial Total Wet Tensile=ITWT (g_(f)/inch)=Peak Load_(MD) (g_(f))/2(inch_(width))+Peak Load_(CD) (g_(f))/2 (inch_(width))

The Initial Total Wet Tensile value is then normalized for the basisweight of the strip from which it was tested. The normalized basisweight used is 36 g/m², and is calculated as follows:Normalized {ITWT}={ITWT}*36 (g/m²)/Basis Weight of Strip (g/m²)

If the initial total wet tensile of a polymeric structure comprising acrosslinking system of the present invention is at least 1.18 g/cm (3g/in) and/or at least 1.57 g/cm (4 g/in) and/or at least 1.97 g/cm (5g/in), then the crosslinking system is acceptable and is within thescope of the present invention. Preferably, the initial total wettensile is less than or equal to about 23.62 g/cm (60 g/in) and/or lessthan or equal to about 21.65 g/cm (55 g/in) and/or less than or equal toabout 19.69 g/cm (50 g/in).

D. Contact Angle Test Method

Contact angle testing is performed on a Fibro DAT high speed contactangle measurement device supplied by Thwing Albert Instrument Company.The test is run to a timeout of 0.1 minutes and applies a 32 micro-literdrop of water on the surface of a fibrous structure sample. The highspeed images obtained by the Fibro DAT are then computer analyzedgenerating a graphical representation of contact angle vs. time. Anaverage of five measures is taken and the contact angle at time equalsone second is used as the reference point. Therefore, a contact angle of40° after 1 second means that the contact angle is measured 1 secondafter the reference point is measured.

E. Wet Bulk Test Method

For the purposes of this document “wet bulk” is defined as the ratio ofthe initial height of a stack of sample squares of dry fibrousstructures to the height of the same stack after the stack has beenthoroughly wetted. The height of the stack is measured with the aid of adigital micrometer (Mitutoyo Series 543 Absolute Digimatic Indicator,Mitutoyo Corporation, Kanagawa, Japan) supported on a stable test stand.The internal spring of the micrometer must be disconnected so as tominimize loading on the stack. The micrometer is fitted with a 1 inchdiameter test foot. Other equipment needed include a Petri dish having adiameter of 100 mm×15 mm and a section of non-stick Teflon® mesh havingopenings of approximately 0.25 in (0.635 cm) coarse nylon screen cut tofit inside the Petri dish, both items are commercially available fromVWR Scientific.

The test procedure includes the following steps. The screen is placedinside the Petri dish and the Petri dish is placed on the base of thetest stand—centered under the micrometer test foot. The micrometerassembly is then lowered until the test foot comes into contact with thescreen. The micrometer is then zeroed. The fibrous structure(s) to betested is cut into 1 inch×1 inch (2.54 cm×2.54 cm) sample squares. Afterraising the micrometer test foot, eight (8) sample squares are stackedone on top of the other in a uniform arrangement and placed on thescreen in the Petri dish under the micrometer test foot. The micrometertest foot is then gently lowered onto the stack of sample squares. Theinitial micrometer reading is then recorded. Next, 50 ml of deionizedwater is slowly added in a controlled manner such that all 50 ml areadded over a period of about 3 seconds to the Petri dish such thatlittle or no water contacts the stack of square samples as a result ofthe addition. After 30 seconds the final height of the stack of samplesquares is recorded. If the entire stack of sample squares is fullywetted (no dry spots within the samples that would affect the reading)the measurement is over. If the entire stack of sample squares is notfully wetted wait an additional 60 seconds then record the final height,the measurement is then over. If the entire stack of sample squares isstill not fully wetted abort the test and record that the stack ofsamples squares was not fully wetted. Repeat test, if necessary.

Calculate the wet bulk by dividing the final height of the stack ofsample squares by the initial height of the stack of sample squares andmultiply by 100% which provides the wet bulk of the fibrous structure asa percent of dry bulk.

F. Wet Yield Stress Test Method

Fibrous structure samples to be measured are cut into 20 mm disks andweighed to the nearest 0.1 mg. The stack of fibrous structure disks areloaded and centered in the sample cup of a Reologica Stresstechrheometer equipped with a Sealed Cell. The rheometer fixture is a 20 mmdiameter parallel plate fixture with serrations of 0.3 mm deep and 0.6mm apart. Water is added to the sample using a 1000 μL mechanicalpipette (Eppendorf Pippetteman) such that the ratio of water mass tofibrous structure mass is 3.5. The sample is then placed in therheometer and the cell pressure is brought up to 10 psig. To run thetest, the normal force sensor of the rheometer is zeroed and the gapbetween the two parallel plates is reduced until the normal forceexerted by the top plate is 3 Newtons. At this point, the gap is heldconstant for the duration of the test. After a 30 second equilibrationtime, the Wet Yield Stress Test is commenced with the followingsettings:

Initial gap: 4 mm gap for speed limit of head approach 3 mm limitingspeed of head approach 0.0305 mm/s Equilibration time before starting 30seconds stress ramp stress ramp 5 to 10,000 Pa, Logarithmically Time forstress ramp 340 seconds measurement steps 34 position resolution settingAuto inertial compensation 100% maximum allowed shear rate 300 s⁻¹

The test results in a graph of stress vs. strain. Read the Wet YieldStress number off the graph and/or rheometer for a particular Strain.

Method G. Fiber Diameter Test Method

A web comprising fibers of appropriate basis weight (approximately 5 to20 grams/square meter) is cut into a rectangular shape, approximately 20mm by 35 mm. The sample is then coated using a SEM sputter coater (EMSInc, Pa., USA) with gold so as to make the fibers relatively opaque.Typical coating thickness is between 50 and 250 nm. The sample is thenmounted between two standard microscope slides and compressed togetherusing small binder clips. The sample is imaged using a 10× objective onan Olympus BHS microscope with the microscope light-collimating lensmoved as far from the objective lens as possible. Images are capturedusing a Nikon D1 digital camera. A Glass microscope micrometer is usedto calibrate the spatial distances of the images. The approximateresolution of the images is 1 μm/pixel. Images will typically show adistinct bimodal distribution in the intensity histogram correspondingto the fibers and the background. Camera adjustments or different basisweights are used to achieve an acceptable bimodal distribution.Typically 10 images per sample are taken and the image analysis resultsaveraged.

The images are analyzed in a similar manner to that described by B.Pourdeyhimi, R. and R. Dent in “Measuring fiber diameter distribution innonwovens” (Textile Res. J. 69(4) 233-236, 1999). Digital images areanalyzed by computer using the MATLAB (Version. 6.3) and the MATLABImage Processing Tool Box (Version 3.) The image is first converted intoa grayscale. The image is then binarized into black and white pixelsusing a threshold value that minimizes the intraclass variance of thethresholded black and white pixels. Once the image has been binarized,the image is skeltonized to locate the center of each fiber in theimage. The distance transform of the binarized image is also computed.The scalar product of the skeltonized image and the distance mapprovides an image whose pixel intensity is either zero or the radius ofthe fiber at that location. Pixels within one radius of the junctionbetween two overlapping fibers are not counted if the distance theyrepresent is smaller than the radius of the junction. The remainingpixels are then used to compute a length-weighted histogram of fiberdiameters contained in the image.

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be considered as an admission that it is prior artwith respect to the present invention. Terms or phrases defined hereinare controlling even if such terms or phrases are defined differently inthe incorporated herein by reference documents.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A polymeric structure derived from a hydroxylpolymer-containing composition comprising: a. an aqueous mixturecomprising a hydroxyl polymer; and b. a hydrophile component comprisingan organosulfosuccinate.
 2. The polymeric structure according to claim 1wherein the hydroxyl polymer-containing composition further comprises acrosslinking system comprising a crosslinking agent.
 3. The polymericstructure according to claim 1 wherein the hydroxyl polymer-containingcomposition further comprises a lipophile component.
 4. The polymericstructure according to claim 3 wherein the hydrophile componentfacilitates dispersibility of the lipophile component in the aqueousmixture.
 5. The polymeric structure according to claim 1 wherein thepolymeric structure exhibits a contact angle of less than about 40°after 1 second.
 6. The polymeric structure according to claim 1 whereinthe polymeric structure is in the form of a fiber having a diameter ofless than about 50 μm.
 7. The polymeric structure according to claim 1wherein the hydroxyl polymer comprises a hydroxyl polymer selected fromthe group consisting of: starch, starch derivatives, cellulosederivatives, chitosan, chitosan derivatives, polyvinylalcohols, gums,arabinans, galactans, proteins and mixtures thereof.
 8. The polymericstructure according to claim 7 wherein the hydroxyl polymer comprisesstarch.
 9. A fibrous structure comprising one or more polymericstructures according to claim 1 wherein at least one of the polymericstructures is in the form of a fiber form.
 10. A single- or multi-plysanitary tissue product comprising a fibrous structure according toclaim
 9. 11. The single- or multi-ply sanitary tissue product accordingto claim 10 wherein the tissue product exhibits a wet yield stress offrom about 1000 to about 6000 Pa at a strain of at least about 1 toabout
 10. 12. The single- or multi-ply sanitary tissue product accordingto claim 10 wherein the tissue product exhibits a wet bulk of at leastabout 40% of the dry bulk.
 13. A method for making the polymericstructure according to claim 1 comprising the steps of: a. providing ahydroxyl polymer-containing composition comprising an aqueous mixturecomprising a hydroxyl polymer and a hydrophile component comprising asulfosuccinate; and b. polymer processing the hydroxylpolymer-containing composition to form the polymeric structure.
 14. Themethod according to claim 13 wherein the aqueous mixture furthercomprises a crosslinking system comprising a crosslinking agent.
 15. Themethod according to claim 13 wherein the sulfosuccinate comprises anorganosulfosuccinate.
 16. A polymeric structure in the form of a fiberproduced according to the method of claim 13.